Bioethanol Production by Immobilized Yeast

Efrat Shtauber , Department of Chemical Engineering, Biotechnology and Materials, Ariel University, Ariel , Israel
Marina Nisnevitch, Department Of Chemical Engineering, Biotechnology And Materials, Ariel University, Ariel , Israel

Due to a worldwide increase in energy consumption and climate changes, there is a need to find other clean, environmentally safe and effective energy sources. One alternative to fossil fuels is bioethanol, which is produced from plant sources, since it does not contribute to greenhouse gas accumulation. Plants produce carbon compounds via photosynthesis through consumption of carbon dioxide from the air. Carbon emission resulting from combustion of bioethanol is balanced by this consumption. Traditional plant sources for bioethanol production are corn and sugarcane. However, in countries with limited agricultural areas, bioethanol can be produced from agricultural wastes and surplus products by fermentation with yeasts, such as Saccharomyces cerevisiae and Pichia stipitis, where the former can convert hexoses into bioethanol and the latter can convert both hexoses and pentoses. Continuous fermentation of extracts from plant biomass has multiple advantages over batch bioethanol production. The current work is dedicated to immobilization of Saccharomyces cerevisiae and Pichia stipitis and designing a continuous process of bioethanol production. In this work, it is shown that both types of yeasts, immobilized in calcium alginate gel, are capable of producing bioethanol with a yield of up to 0.43 g per g of saccharides or 84% of the theoretical yield